Sulfur Dioxide Derivative Prevents the Prolongation of Action Potential During the Isoproterenol-Induced Hypertrophy of Rat Cardiomyocytes

Exogenous SO2 is toxic especially to the pulmonary and cardiovascular system, similar to nitric-oxide, carbon-monoxide, and hydrogen-sulfide. Endogenous SO2 is produced in many cell types. The SO2 content of the rat heart has been observed to substantially decrease during isoproterenol-induced hypertrophy. This study sought to determine whether an SO2 derivative could inhibit the prolongation of action potentials during the isoproterenol-induced hypertrophy of rat cardiomyocytes and explore the ionic currents. Alongside electrocardiogram recordings, the voltage and current-clamped measurements were conducted in the enzymatically isolated left ventricular cardiomyocytes of Wistar rats. The consistency of the results was evaluated by the novel mathematical electrophysiology model. Our results show that SO2 significantly blocked the prolongation of QT-interval and action potential duration. Furthermore, SO2 did not substantially affect the Na+ currents and did not improve the decreased steady-state and transient outward K+ currents, but it reverted the reduced L-type Ca2+ currents (I CaL) to the physiological levels. Altered inactivation of I CaL was remarkably recovered by SO2. Interestingly, SO2 significantly increased the Ca2+ transients in hypertrophic rat hearts. Our mathematical model also confirmed the mechanism of the SO2 effect. Our findings suggest that the shortening mechanism of SO2 is related to the Ca2+ dependent inactivation kinetics of the Ca2+ current.